Automatic magnetic key sustaining device for keyboard musical instruments



June 17,1941. J DEZSQ 2,246,434

KUTQMATIC MAGNETIC ,KEY SUSTAINING DEVICE FOR KEYBOARD MUSICALINSTRUMENTS Filed Feb. 29, 1940 2' Sheets-Sheet 1 f9 F M I I 76 (i/ 4 l/4- -QQ JQ Jun e 17, 1941. A DEZSQ 2,246,434

AUTOMATIC MAGNETIC KEY SUSTAINING DEVICE FOR KEYBOARD MUSICALINSTRUMENTS Filed Feb. 29, 1940 2 Sheets-Sheet 2 Patented June 17, 1941DEVICE STRUMENTS FOR KEYBOARD MUSICAL IN Joseph A. Dezso, South Bend;Ind; Application'February 29, 1940', Serial- N; 3211589 (Cl. 8k-441) '7Claims.

This invention relates to an improved device for use on musicalinstruments of the keyboard type for sustaining notes or chords andhaving magnetic means for engaging elements carried by the instrumentkeys for retaining the keys in a depressed position until actuated byother key or keys of the instrument to thereby sustain a note or chordafter the fingers have been removed from the keys striking such note orchord.

Another object of the invention is to provide a device of the characterdescribed includingan electromagnet connected to a source of electriccurrent and energized thereby for attracting metallic elements securedto and depending from the keys of a musical instrument for holding thekeys in a depressed position, said electromagnet being connected incircuit with a plurality of electrical switches each of which is adaptedto be actuated by a partial depressing of one of the" keys for openingthe switch to interrupt the cir=- cult to the electromagnet and tothereby release other keys which may be held depressed.

Still another aim of the inventionis to providea novel form of electricswitch and means for actuating the switch whereby the switch will'beopened by partially depressing a key carrying the aforementioned meansand released by said means to return to a closed positionwhen the key isfully depressed, said means being retractible to pass the switch withoutaffecting its closed position when the key is returned to a-normal;raised'position.

Other objects and advantages of the invention will hereinafter becomemore fully apparent from the following description of the drawings,which illustrate a preferred embodiment thereof, and wherein:

Figure 1 is a transverse sectional view taken through a portion of theframework of a keyboard type musical instrument, such as a piano, andshowing two of its keys in elevation and the invention, associatedtherewith andshown partly" in elevation and partly in cross section,

Figure 2 is a horizontal sectional view-taken substantially along theplane of the line 2-2 of Figure 1, c. c

Figure 3 is a view similar to Figure 1 showing one of the keys in apartly depressed position for interrupting the electric circuit to theelectromagnet.

Figure 4 is a view similar to Figure 3 showing a key in a fullydepressed position with the switch in a released and closed position tocomplete'the circuit to the electromagnet,

Figure 5 is a longitudinal vertical" sectional view taken substantiallyalong the plane of the line'5'-5 of Figure 1',

Figure '6 is a perspective view of the insulating block in which theswitches and electromagnet are mounted;

Figure '7 i's'a similar view of one of the supporting hangers orbrackets,

Figure "his a similar view of one of the metallic members which areadapted to be attracted by the electromagnet, and

Figure 9 is'a diagrammatic viewof the circuit inwh'iclitheelectromagnet' and switches are connected;

Referring? more particularly to the drawings wherein like referencecharacters designate like or corresponding parts throughout thedifferent views, for the purpose of illustration, l0 designatesgenerally aportion' of the framework of a keyboard type musicalinstrument such as a piano havinga keyboard, designated'generally H withthe long natural tone keys l2 and the short, sharp and flat tone keys13, which parts are shown merely toillustrate the application of thetone sustaining means, designated generally l4 and comprising theinvention, which will hereinafter'be described;

The tone sustaining attachment 14 includes a block P5 of insulatingmaterial which is mounted in" the frame HF longitudinally thereof,beneath the-keys l2 and slightly beyond the free ends of the keys l3, asbest seen in Figures 1, 3 and 4. Referringto-Figure 6, the block 15 isprovided with a plurality of spaced recesses 16' which open outwardly ofits top and which extend downwardly' to adjacent its bottom to form abottom or lower portion I7 and a plurality of Walls l8 disposed" betweenthe recesses The bottom portions of the outer ends of the walls 18 arecutaway as indicated at I9 toreceive a bar of metal 20" which extendssubstantially the length of the'insulated block l5 and which issupported by' the lower portion or bottom H, as best seen in Figures 1,3-and 4. The adjacent recesses l6 are connected'by slots 21' whichextend diagonally through th'eupper portions of the walls I8. Acontact'element 22- is disposed in each of the recesses l6 adjacent itsupper forward portion and is suppo'rtedby' a fastening 23 mounted in anadjacent wall l8: and to which is connected an arm 1'4 which extendsfrom the contact element" 22 to thereby fixedly' support the contactelements 22 relatively to the block l5.

As best seen in Figures 1, 3 and 4, an arm 25 is disposed in ea'ch'ofthe'r'ecesses l6 and pivotally connected" at one end by means'of apin 26to a pivoted arm 25 mounted on the'same wall I8 to urge the free end ofsaid arm upwardly to cause its contact element 21 to engage the contactelement 22 mounted on the same .wall I3, .as best I I with which thesprings 46 are associated to break seen in Figures 1 and 4. AsseeninfFigureZ'ea'ch of the contact elements 22 is connected by means ofa conductor wire 29 which extends through a slot 2|, to the pivot pin 26on the wall" I8 directly I to the right of the wall I8 on which thecontact 1 member 22 is mounted, so thateach c oritact member 22 isconnected by a wire 23 to the next adjacent pivot pin 26 to its right,as illustrated diagrammatically in Figure 9, andas the arms 25 formconductors between the" pivot pins 26 and,

the contact points 21 these parts are all connected together. 22 and 21,the arm 25 associated therewitlifand its pivot pin 26 combine toform anelectr'icswitch, designated generally 33. As seen in'Figure.9,'a

circuit is shown wherein the switches 30 area-ll, connected in circuitwith'o'ne' another and with i the electromagnet 23 which circuitinclu'desa conductor3I which extends from a source of electrical currentthrough a transformer 32 by means of which the current is stepped, down,thence to one end of the bar 20 forming the electromagnet, A conductor33 extends from the opposite end of the bar 20 t th i ot pin 26, of thelast switch 30 at one end of the insulating block I5- The'i otherswitches 30 are connected to'one another,

as heretofore cxplained, by the;conduc'tors 29 and the contact element22 of the switch 33 at the opposite end of the block I5 is connected toa conductor 34 which extends back through the transformer 32and back tothe source of electrical current, not shown,to ground the circuit.

Conductor 34 is preferably providedlwith a manually controlled switch 35by means of whichthe circuit may be opened when the instrument on whichthe invention I4 is mounted is not in use and for playing the instrume twithout employing the attachment I4. I v

A bracket or hanger 36 has one endv 3?. provided with an elongated slot38 to receive a screw fastening 39 for securing it tofthe' underside'ofa key I2 or I 3. A hanger 36 is thus secured to each of the keys I2 andI3 and said hangers are disposed in substantially a straight line withthose secured to the keys I3 disposediad jacent' their free ends andthose'secured'to the longer keys I2 disposed intermediateofTtheir'endsLBy means of the slots 38, the brackets or'hanger's 35 may be adjustedlongitudinally of the keys I2 and I3 to move them, toward or -away fromthe block I5 for a purpose which will'hereinafte'r be explained. Theopposite, depenrfing ends 48 ,of

the hangers 35 are disposed substantially at right angles to the ends 31and are provided, adjacent their lowerends, with longitudinal'slots' IIand adjacent their opposite ends with openings 42. A metallic member'43'issecured to each of the ends 4!] by means of ascrew fastening-M whichextends through the slot 4 I into a threaded opening in the member 43.Slots 4I provide means whereby the members 43 may be adjustedlongitudinally of the ends MI. A leaf spring '45 ;is

Each pair of contact elements secured at one end by means of afastening, 47, which engages the opening 42 to each of the ends 45. Leafsprings 46 project downwardly and outwardly from the brackets or hangers36 and are adapted to be disposed with their free ends directly abovethe free ends of the arms 25 of the switches 30 when the keys I2 and I3are in their normal, substantially horizontal positions.

fAssuming the switch 35 to be closed, a key I2 or I3 or a group of saidkeys are depressed by the fingers of the player and as the keys begin to7 move downwardly the springs 46 of the hangers 36, carried by saidkeys, will depress the arms 25 the connection between the contacts 2 2and 2'! of the switches 30 of which said arms 25 form a part.

the springs 46 will be swung out of engagement with the free ends of theaforementioned arms 25 to release said arms to allow the contacts 22 and2'! of their switches 39 to return to a closed positionto complete thecircuit, as' seen in Figure 9, to cause the electricity passing throughthe bar 20 to magnetize the' bar to cause it to function as anelectromagnet for attracting the metallic members '43 of the depressedkeys I2 and I3 to hold these keys in a depressed position, as seen inFigure 4, to thereby sustain the notes or chords struck by said keys.When another key I2 or I3 or a group of said keys are pressed down,their springs 43 will similarly engage and depress the arms 25associated therewith. As soon as any one of the other arms 25 is moveddownwardly to cause its contact point 21 to move out of engagement withits contact point 22 the circuit through theelectromagnet 20 will bebroken to demagnetizeit to release the members 43 which have been heldattracted thereby so that their keys I2 and I3 may return to a fullyraised position with their springs 46 retracting to pass over the freeends of the arms 25 with which they are associated. It will thus be seenthat any one of the keys [2 or I3may be partially depressed forreleasingv any number of the keys which are held in a depressed positionafter which the partially depre'ssedkey may be released to return to araised position It is to be understood that a switch 33 is associatedwith each of the hangers or brackets 36, oneof which is connected toeach of the keys I2 and I3. The brackets or hangers 36'may be "adjusted,as heretofore explained, relatively to the keys I2 and I3 for properlypositioning thesprings 46 for engagement with the arms 25and the members43, which are disposed transversely of the bracket ends 43 may beadjusted longitudinally thereof for properly positioning them:relatively to the bar or electromagnet 20.

Various modifications and changes arec'ontemplated and may obviously beresorted to as only a preferred embodiment of the invention has beendisclosed, 7

I claim as my invention:

-1. An attachment for keyboard type instruments comprising a block ofinsulating material mounted in an instrument frame, an electromagnetdisposed in said block and connected .to a source of electrical current,hangers connected to and depending from each of the keys of theinstrument and provided with metallic blocks arand a spring fingerattached to each of said hangers, and extending outwardly and downwardlytherefrom, for engaging and opening the switches when the keys are in apartially depressed position to break the circuit to the ma net.

2. An attachment for keyboard type musical instruments comprisingelectromagnetic means connected to a source of electrical current anddisposed within the frame of a musical instrument and beneath itkeyboard, hangers, having metallic members secured to their dependingends, connected to and depending from the keys of the keyboard, aidmetallic members being arranged to be attracted by the electromagneticmean when their supporting keys are in a depressed position, a pluralityof switches connected in circuit with said electromagnetic means, and aspring finger attached to each of said hangers, and extending outwardlyand downwardiy therefrom, for depressing and opening the switches, whenthe keys are in a partially depressed position, whereby saidelectromagnetic means will be deenergized by partially depressing anyone of the keys.

3. A tone sustaining attachment for keyboard type musical instrumentscomprising an electromagnet connected to a source of electric current,metallic members supported by and depending from the keys of a musicalinstrument and movable, by depressing the keys, into a position adjacentto the electromagnet to be attracted thereby to retain the depressedkeys in a depressed position, a plurality of switches connected incircuit with said electromagnet, and a spring finger extendingdownwardly and outwardly from each of said keys, for engaging andopening the switches when the keys are in a partially depressed positionfor deenergizing the electromagnet.

4. A tone sustaining attachment for keyboard type musical instrumentscomprising a block of insulating material mounted in the frame of amusical instrument and beneath the keyboard thereof, an electromagnetmounted in said block and connected to a source of electrical current, aplurality of electric switches mounted in spaced apart relationshiprelatively to each other in said insulated block, said switches beingconnected in circuit with said electromagnet, hangers secured to anddepending from the keys of the instrument, a metallic member connectedto the depending end of each of said hangers, said metallic membersbeing arranged to be attracted by the electromagnet when theirsupporting keys are in a fully depressed position to retain said keysdepressed, and a spring finger attached to and projecting downwardly andoutwardly from each of said hangers, for engaging and opening a switchwhen its supporting key is partially depressed for interrupting thecircuit to the electromagnet for releasing the depressed keys.

5. A device as in claim 4, said electric switches each including a fixedcontact point and a pivotally mounted contact element having a contactpoint for engaging the fixed contact point, spring mean for normallyraising said pivotally mounted contact element for closing the switch,and said contact elements being engageable by said spring fingers, whenthe keys are partially depressed, for interrupting the circuit, saidspring fingers being movable out of engagement with the pivotallymounted contact elements when the keys are moved to a fully depressedposition.

6. A device as in claim el, said switches each including a pivotallymounted contact element, to be engaged by a spring finger when itssupporting key is partially depressed to open the circuit to the magnet,said spring fingers moving out of engagement with said contact elementswhen the keys are fully depressed to permit the switches to return to aclosed position for energizing the magnet, and said spring fingers beingretracted by said contact elements to move past said elements when thekeys are returned to a raised, normal position.

'7. A device as in claim 4, each of said hangers being provided withmeans for longitudinally adjusting it relatively to its supporting keyfor moving the hangers toward and away from the insulated block, andmeans, on said hangers, for longitudinally adjusting said metallicmembers relatively thereto.

JOSEPH A. DEZSO.

